157 



raised parallelograms, separated by the deep longitudinal and 

 horizontal furrows. 



Greatest diameter, 22; less, 19 ; alt. 15 millimetres. 



Geographical Distribution. Found in Oregon Territory. 



Remarks. This shell I found in the collection of my father, 

 Dr. Amos Binney. It was labelled H. Nickliniana, Lea. var., 

 and as such is figured in the terrestrial moUusks. I cannot believe, 

 however, that any species can admit of varieties differing so much 

 as this does from NicMiniana. To Mr. Lea's figure and descrip- 

 tion it bears no resemblance whatever, either in shape or sculp- 

 turing. 



It may readily be distinguished among the Helices of the Pa- 

 cific coast, by its grayish, heavy shell, its thickened lip, and above 

 all, by the peculiar markings of the surface. 



Dr. A. A. Hayes exhibited a specimen of rock guano, 

 from a lately-discovered deposit on an island not far dis- 

 tant from the main land in the Atlantic Ocean. 



Dr. Hayes called attention to this substance chiefly, as an illus- 

 tration offered of the solution and subsequent deposition of phos- 

 phate of lime from decomposing bones. Eeferring to a paper which 

 he lately read here, in explanation of the chemical action, he showed 

 that the solution of bibasic phosphate, eliminated from tribasic 

 phosphate of lime, had penetrated into and cemented not only 

 the phosphate of comminuted bones, but had united a mass of 

 bivalve shells ; in some cases actually i*emoving the excess of 

 carbonate of lime, leaving a partly bibasic phosphate behind. 



He had examined a number of cases of this transference, and 

 found sand and gravel aggregated by the phosphate which had 

 been removed from bone-phosphate, through the agency of cai'- 

 bonic and crcnic acids, formed in the humid decomposition of the 

 animal matter present in the bird droppings, — so as to form a 

 compound rock. 



The facts already observed prove that mineral masses contain- 

 ing phosphate of lime, may be thus formed from animal phosphate 

 of lime, and present all the characters which we recognize in the 

 phosphate of lime engaged in the oldest slates. Additional inter- 

 est has been given to this subject, by communications from Prof. 



